BOSTON — In hindsight, it was too much to ask for the Nets to come into TD Bank Garden without Deron Williams, without Kris Humphries and without Brook Lopez and beat the Boston Celtics.

It would have been nice, though, if the game was all they lost.

Unfortunately, though, the 89-70 setback to the Celtics — their sixth loss in a row — was the least of the Nets’ worries tonight. The bigger story was that MarShon Brooks, who started the game in place of Williams, left the game in the fourth quarter after twisting his left ankle.

And Damion James, the starting small forward, also left with an injury — he stepped on Paul Pierce’s foot and rolled his right ankle near the end of the first half and did not return.

“It’s just a little tweak — it could happen to anybody,” James said. “I’ll be good to go (tomorrow).”

Brooks said he first twisted the ankle late in the first half, but he got it retaped and tried to play the second half.

After scoring 15 points in the first half, the rookie was hampered by the ankle and stymied by the Celtics’ defense, and midway through the fourth quarter, he fired up a turnaround jumper that missed, and when he came down he stepped on the Celtic player’s foot and rolled the ankle. He stayed down, grabbed the ankle, and then eventually got up slowly and limped off with 7:54 to play.

Brooks still ended up leading the Nets with 17 points, which is good for him, but not so much for the Nets. Jordan Farmar, with 11 off the bench, was the only other Net to reach double figures in scoring.

Meanwhile, with Ray Allen out with flu-like symptoms, Pierce led all scorers with 24 for the Celtics. Brandon Bass had 15 points and 13 rebounds off the bench, and Kevin Garnett had 14 points and 12 rebounds.

The Nets actually led, 35-34, at halftime, but they managed just 12 points in the third quarter, and that was enough to knock them out of the game.

“They really turned up the pressure, clamped us down, and smothered us,” Nets coach Avery Johnson said. “They’re a championship team with a lot of experience.”

The Nets are a long way from that, which is something that has seemed to frustrate Williams as the losses piled up in recent days.

“I don’t know what my biggest losing streak is, but I never started a season like this, so it’s very, very unusual for me — very frustrating, very tough,” Williams said at pregame shootaround.

“But at the same time, it’s all unusual circumstances. We have a new team, pretty much (and) still have a lot to add. I just try to look at the bigger picture, as much as possible, but still stay focused on trying to get some wins.”

Williams expressed confidence that general manager Billy King will be able to find a way to improve the Nets’ roster enough to convince him to re-sign with the Nets when he becomes a free agent this summer.

“I’m very confident — very confident in what Billy’s doing,” he said. “And that’s why I’m trying to be — I am being patient. I understand, like I said, there’s a bigger picture.”

Williams was injured on an elbow by Indiana Pacers forward Tyler Hansbrough in Monday’s game. He said X-rays were negative, but his ribs were more sore this morning than they were the day before, which was something he didn’t expect.

“It’s pretty sore,” he said. “Coach and Timmy (Walsh, the Nets’ athletic trainer) thought it was best for me to sit out. If I got hit on it again, it wouldn’t be good.”